The technology relates a technique that performs data communication between a plurality of communication bodies. In particular, the technology relates to a technique useful in performing data communication safely by reducing a possibility of detection by a third party.
There are situations where data is not receivable directly from a transmission-source communication body upon performing data communication between a plurality of communication bodies. For example, the data is not receivable directly when transmission of the data is interrupted by terrain.
To address such situations, a technique has been proposed in which a communication body other than the transmission-source communication body relays, to a transmission-destination communication body, the data received from the transmission-source communication body. For example, reference is made to Japanese Unexamined Patent Application Publication (JP-A) No. 2004-336408.